The factories of fertilizers with nitrogen and others discharge large quantities of much diluted waste water, with cation and anion contents. Thus, in the manufacture of ammonium nitrate, there is discharged waste water containing ammonia and ammonium nitrate; in the manufacture of complex fertilizers with N, P, K, the waste water contains ammonia, ammonium nitrate and triammonium phosphate, some calcium nitrate, and others.
The fast development of the industry of fertilizers with nitrogen, and others, called for the finding of an advantageous technical and economic method for the purification of this waste water, which strongly pollutes the river and lake waters into which it is discharged, giving rise to heavy damages to the piscicultural fauna, to the flora and to the human organisms they get in touch with.
Among the known technological processes for purification and rendering available, viz: biological purification, concentration of waste water, in plants for evaporation in stages, the electro-dialysis in cells with selective ion exchange membranes, ammonia stripping by steam or air, demineralization by means of ion exchangers is discontinuous fixed bed or in continuous moving bed, it is appreciated that the process of ion exchange in moving (continuous) bed presents the most advantageous solution.